PCR updated the County's Significant Ecological Areas (SEA) program for the first time since 1976, as a major component of its 2000 General Plan Update Program. The study area included all incorporated lands within the approximately 4,000 square miles bound by County lines. PCR completed a series of scientific tasks to meet the objectives of the assignment, including: an extensive review of scientific literature, regional data bases and natural resource planning documents; interviews with state and federal resource agency representatives; public outreach entailing 21 workshops throughout the County; mapping of SEAs onto aerial imagery for digitization into a GIS data base; development of land management guidelines that are consistent with identified regional conservation goals; and documentation in the form of a 14-volume publication.

The study resulted in a scientifically rigorous planning tool to delegate sustainable SEA boundaries and improve their overall management. The study is intended to guide project applicants, the Los Angeles County Department of Regional Planning, the County's Significant Ecological Area Technical Advisory Committee, and County decision-makers in sound stewardship of the County's biological diversity.